Abstract
A method for measuring wear of a rail (20) comprises detecting a first set of wheel signals (SW1) by a wheel sensor (21) mounted to the rail (20), determining a first average wheel signal (AV1) of the first set of wheel signals (SW1), detecting at least one second set of wheel signals (SW2) by the wheel sensor (21), where the second set of wheel signals (SW2) is detected after detecting the first set of wheel signals (SW1), determining a second average wheel signal (AV2) of the second set of wheel signals (SW2), and determining a difference signal (DIF) given by the difference between the second average wheel signal (AV2) and the first average wheel signal (AV1), wherein a wheel signal is detected when a wheel (22) of a rail vehicle passes the wheel sensor (21). Furthermore, an evaluation system (23) for measuring wear of a rail (20) is provided.
Claims
1. A method for measuring wear of a rail, the method comprising: detecting a first set of wheel signals by a wheel sensor mounted to the rail, determining a first average wheel signal of the first set of wheel signals, detecting at least one second set of wheel signals by the wheel sensor, where the second set of wheel signals is detected after detecting the first set of wheel signals, determining a second average wheel signal of the second set of wheel signals, and determining a difference signal given by the difference between the second average wheel signal and the first average wheel signal, wherein a wheel signal is detected when a wheel of a rail vehicle passes the wheel sensor.
2. The method according to claim 1, wherein the first set of wheel signals and the at least one second set of wheel signals comprise the same number of wheel signals.
3. The method according to claim 1, wherein the first set of wheel signals and the at least one second set of wheel signals comprise at least ten wheel signals, respectively.
4. The method according to claim 1, wherein the first average wheel signal is a reference signal for a state of no or a known wear of the rail.
5. The method according to claim 1, wherein the difference signal (DIF) relates to the state of wear of the rail.
6. The method according to claim 1, wherein a plurality of difference signals is determined for the differences between a plurality of second average wheel signals and the first average wheel signal.
7. The method according to claim 1, wherein an output signal is provided if the difference signal is larger than a predetermined threshold value.
8. The method according to claim 1, wherein the first average wheel signal comprises the average value of the maximum amplitude of the wheel signals of the first set of wheel signals.
9. The method according to claim 1, wherein the second average wheel signal comprises the average value of the maximum amplitude of the wheel signals of the second set of wheel signals.
10. The method according to claim 1, wherein intermediate second average wheel signals of subsets of the second set of wheel signals are determined by the wheel sensor and the second average wheel signal is determined from the intermediate second average wheel signals by an evaluation unit.
11. The method according to claim 1, wherein the second set of wheel signals is provided to an evaluation unit, where the second average wheel signal is determined.
12. An evaluation system for measuring wear of a rail, the evaluation system comprising: an input for receiving signals from at least one wheel sensor mounted to the rail, a memory unit, where a first average wheel signal of a first set of wheel signals is saved, an averaging unit that is configured to determine a second average wheel signal of a second set of wheel signals, and a comparator unit that is configured to determine a difference signal given by the difference between the second average wheel signal and the first average wheel signal, wherein each wheel signal relates to a wheel of a rail vehicle passing the wheel sensor, the averaging unit is connected to the input, and the comparator unit is connected to the memory unit and the averaging unit.
13. The evaluation system according to claim 12, the evaluation system further comprising an output for providing an output signal if the difference signal is larger than a predetermined threshold value.
14. The evaluation system according to claim 12, wherein the averaging unit comprises an evaluation unit that is configured to determine the second average wheel signal.
15. The evaluation system according to claim 12, wherein the averaging unit comprises the wheel sensor and an evaluation unit, wherein the wheel sensor comprises a further averaging unit that is configured to determine intermediate second average wheel signals of subsets of the second set of wheel signals, and wherein the wheel sensor is connected to the evaluation unit.
Description
[0045] The following description of figures may further illustrate and explain exemplary embodiments. Components that are functionally identical or have an identical effect are denoted by identical references. Identical or effectively identical components might be described only with respect to the figures where they occur first. Their description is not necessarily repeated in successive figures.
[0046] FIGS. 1 and 2 show side views of an exemplary embodiment of a wheel sensor mounted to a rail.
[0047] In FIG. 3 exemplary wheel signals are plotted.
[0048] FIGS. 4, 5 and 6 schematically show exemplary embodiments of the method for measuring wear of a rail.
[0049] FIGS. 7, 8, 9 and 10 show exemplary embodiments of the evaluation system for measuring wear of a rail.
[0050] In FIG. 1 a side view of an exemplary embodiment of a wheel sensor 21 is shown. The wheel sensor 21 is mounted to a rail 20. The wheel sensor 21 is mounted to the rail 20 via a mounting system 31. The mounting system 31 comprises a carrier 32 on which the wheel sensor 21 is mounted. The carrier 32 is connected to a clamp 33 which extends below the rail 20. The clamp 33 is fixed to the rail 20 at a bottom side 34 of the rail 20, where the bottom side 34 faces away from the side where wheels 22 of passing rail vehicles can be positioned. The wheel sensor 21 is supplied with energy via a cable 35 connected to the wheel sensor 21.
[0051] In FIG. 1 a cross section through the rail 20 is shown. On a top surface 36 of the rail 20 a wheel 22 of a rail vehicle is positioned. FIG. 1 only shows a part of the wheel 22. The top surface 36 of the rail 20 faces away from the bottom side 34. The top surface 36 of the rail 20 is arranged at a top part 38 of the rail 20.
[0052] In the situation of FIG. 1 the rail 20 is relatively new. Therefore, wear of the rail 20 can be neglected. At this initial stage the top surface 36 is spaced from a top side 37 of the wheel sensor 21 by a distance d. The top side 37 of the wheel sensor 21 is spaced from the wheel flange of the wheel 22 by a distance f. The wheel sensor 21 is mounted to the rail 20 in such a way that wheels 22 of passing rail vehicles do not touch the wheel sensor 21.
[0053] FIG. 2 shows another side view of the exemplary embodiment of the wheel sensor 21. In comparison to the situation shown in FIG. 1, in this case the rail 20 has been used for a while so that the rail 20 shows wear. This means, the height of the top part 38 of the rail 20 is reduced. By a large number of rail vehicles passing the rail 20 a part of the top part 38 is removed so that the thickness of the top part 38 is reduced. This means, the wear of the rail 20 takes place in a vertical direction z. Therefore, also the distance d between the top surface 36 of the rail 20 and the top side 37 of the wheel sensor 21 is reduced in comparison to the situation shown in FIG. 1. The distance f between the wheel flange and the top side 37 of the wheel sensor 21 is reduced as well. In order to avoid a damage of the wheel sensor 21 by wheels 22 of passing rail vehicles it is necessary to lower the position of the wheel sensor 21 with respect to the top surface 36 of the rail 20.
[0054] In FIG. 3 examples of wheel signals are plotted. On the x-axis the distance is plotted in mm. On the y-axis the current is plotted in mA. The wheel sensor 21 comprises two sensors which each are inductive sensors. The change in the current plotted on the y-axis indicates the movement of electrically conductive material in the vicinity of the wheel sensor 21. In this way, the presence of a wheel 22 of a rail vehicle can be detected. Each of the sensors detects one wheel signal per wheel 22. Each wheel signal comprises a plurality of amplitude values that are plotted on the y-axis in FIG. 3. Moreover, each wheel signal has a maximum amplitude value. The maximum amplitude value is the value which differs the most from the value for the situation that no wheel 22 is present close to the wheel sensor 21. In other words, the maximum amplitude value is the value of the wheel signal that differs the most from an initial value. For the first one of the two sensors the wheel signal drops at around 250 mm. The drop of the wheel signal relates to a wheel 22 passing the wheel sensor 21. The maximum amplitude value is in this case the lowest value on the y-axis of each wheel signal, respectively. For the second one of the two sensors the wheel signal drops at around 350 mm. As the first sensor is mounted spaced apart from the second sensor, the wheel signals of the two different sensors drop at different distances.
[0055] In FIG. 3 for each of the two sensors wheel signals are plotted for different points in time. The dashed lines relate to a state where the rail 20 is relatively new and wear of the rail 20 is negligible. The other three wheel signals are detected after this first wheel signal. The dashed-dotted lines relate to a state of increased wear of the rail 20 in comparison to the state of the dashed line. The dotted lines relate to a state of maximum wear of the rail 20. The maximum amplitude of the wheel signals is different for the different states of wear of the rail 20. This means, the maximum amplitude of the wheel signals can be related to the state of wear of the rail 20. In FIG. 3, as an example the maximum amplitude m is shown for the dotted line, this means for the state of maximum wear of the rail 20.
[0056] FIG. 4 schematically shows an exemplary embodiment of the method for measuring wear of a rail 20. A first step S1 of the method comprises detecting a first set of wheel signals SW1 by a wheel sensor 21 mounted to the rail 20. In each case, a wheel signal is detected when a wheel 22 of a rail vehicle passes the wheel sensor 21. In a second step S2 of the method a first average wheel signal AV1 of the first set of wheel signals SW1 is determined. The first average wheel signal AV1 comprises the average value of the maximum amplitude of the wheel signals of the first set of wheel signals SW1. The first average wheel signal AV1 is a reference signal for a state of no or a known wear of the rail 20. A third step S3 of the method comprises detecting at least one second set of wheel signals SW2 by the wheel sensor 21, where the second set of wheel signals SW2 is detected after detecting the first set of wheel signals SW1. The first set of wheel signals SW1 and the second set of wheel signals SW2 can comprise the same number of wheel signals. For example, the first set of wheel signals SW1 and the second set of wheel signals SW2 comprise at least 10 wheel signals, respectively. In a fourth step S4 of the method a second average wheel signal AV2 of the second set of wheel signals SW2 is determined. The second average wheel signal AV2 comprises the average value of the maximum amplitude of the wheel signals of the second set of wheel signals SW2. The second average wheel signal AV2 can be determined by an evaluation unit 29 to which the second set of wheel signals SW2 is provided. A fifth step S5 of the method comprises determining a difference signal DIF given by the difference between the second average wheel signal AV2 and the first average wheel signal AV1. The difference signal DIF relates to the state of wear of the rail 20. It is further possible that a plurality of difference signals DIF is determined for the differences between a plurality of second average wheel signals AV2 and the first average wheel signal AV1. In the fifth step S5 an output signal is provided if the difference signal DIF is larger than a predetermined threshold value.
[0057] Instead of providing the second set of wheel signals SW2 to the evaluation unit 29 and determining the second average wheel signal AV2 by the evaluation unit, subsets SUB of the second set of wheel signals SW2 can be detected. This means, the wheel sensor 21 can be configured to detect subsets SUB of the second set of wheel signals SW2. Each subset SUB comprises at least two wheel signals. The second set of wheel signals SW2 can comprise several subsets SUB of wheel signals. The wheel sensor 21 can be configured to determine intermediate second average wheel signals IAV2 of the subsets SUB of the second set of wheel signals SW2. This means, the wheel sensor 21 is configured to determine an intermediate second average wheel signal IAV2 for each subset SUB. Subsequently, the second average wheel signal AV2 is determined from the intermediate second average wheel signals IAV2 by the evaluation unit 29.
[0058] FIG. 5 schematically shows an exemplary embodiment of the method for measuring wear of a rail 20. The first set of wheel signals SW1 is detected by the wheel sensor 21 and the first average wheel signal AV1 of the first set of wheel signals SW1 is determined. Subsequently, at least one second set of wheel signals SW2 is detected by the wheel sensor 21 and the second average wheel signal AV2 of the second set of wheel signals SW2 is determined. In a next step, the difference signal DIF given by the difference between the second average wheel signal AV2 and the first average wheel signal AV1 is determined.
[0059] FIG. 6 schematically shows another exemplary embodiment of the method for measuring wear of a rail 20. In comparison to the embodiment shown in FIG. 5 the second average wheel signal AV2 is determined differently. Subsets SUB of the second set of wheel signals SW2 are detected by the wheel sensor 21. For each subset SUB an intermediate second average wheel signal IAV2 is determined by the wheel sensor 21. Subsequently, the second average wheel signal AV2 is determined from the intermediate second average wheel signals IAV2 by the evaluation unit 29. In a next step, the difference signal DIF given by the difference between the second average wheel signal AV2 and the first average wheel signal AV1 is determined.
[0060] FIG. 7 shows an exemplary embodiment of an evaluation system 23 for measuring wear of a rail 20. The evaluation system 23 comprises an input 24 for receiving signals from at least one wheel sensor 21 mounted to the rail 20. The signals can be wheel signals. Each wheel signal relates to a wheel 22 of a rail vehicle passing the wheel sensor 21. The evaluation system 23 further comprises a memory unit 25, where a first average wheel signal AV1 of a first set of wheel signals SW1 is saved. The evaluation system 23 further comprises an averaging unit 26 that is configured to determine a second average wheel signal AV2 of a second set of wheel signals SW2. The averaging unit 26 is connected to the input 24. The evaluation system 23 further comprises a comparator unit 27 that is configured to determine a difference signal DIF given by the difference between the second average wheel signal AV2 and the first average wheel signal AV1. The comparator unit 27 is connected to the memory unit 25 and the averaging unit 26.
[0061] FIG. 8 shows another exemplary embodiment of the evaluation system 23. In comparison to the embodiment shown in FIG. 7 the averaging unit 26 comprises an evaluation unit 29 that is configured to determine the second average wheel signal AV2. The evaluation unit 29 is connected to the input 24, to the memory unit 25 and to the comparator unit 27. Furthermore, the evaluation system 23 comprises an output 28 for providing an output signal if the difference signal DIF is larger than a predetermined threshold value.
[0062] FIG. 9 shows another exemplary embodiment of the evaluation system 23. In comparison to the embodiment shown in FIG. 7 the averaging unit 26 comprises the wheel sensor 21 and an evaluation unit 29. The wheel sensor 21 can be arranged spaced apart from the other components of the evaluation system 23. The wheel sensor 21 is arranged in the vicinity of the rail 20. The wheel sensor 21 can be mounted to the rail 20. The evaluation unit 29 comprises the input 24 of the evaluation system 23 and is connected with the wheel sensor 21 via the input 24. The evaluation unit 29 is further connected to the memory unit 25 and to the comparator unit 27. Furthermore, the evaluation system 23 comprises an output 28 for providing an output signal if the difference signal DIF is larger than a predetermined threshold value.
[0063] The wheel sensor 21 comprises a further averaging unit 30 that is configured to determine intermediate second average wheel signals IAV2 of subsets SUB of the second set of wheel signals SW2. The intermediate second average wheel signals IAV2 are provided to the evaluation unit 29. The evaluation unit 29 is configured to determine the second average wheel signal AV2 from the intermediate second average wheel signals IAV2.
[0064] FIG. 10 shows another exemplary embodiment of the evaluation system 23. In comparison to the embodiment shown in FIG. 9 the averaging unit 26 comprises a plurality of wheel sensors 21 which is indicated by the dotted line between the wheel sensors 21. Each wheel sensor 21 is connected with the evaluation unit 29 via an input 24, respectively. Alternatively, which is not shown, all wheel sensors 21 are connected with the evaluation unit 29 via one and the same input 24.
REFERENCE NUMERALS
[0065] 20: rail [0066] 21: wheel sensor [0067] 22: wheel [0068] 23: evaluation system [0069] 24: input [0070] 25: memory unit [0071] 26: averaging unit [0072] 27: comparator unit [0073] 28: output [0074] 29: evaluation unit [0075] 30: further averaging unit [0076] 31: mounting system [0077] 32: carrier [0078] 33: clamp [0079] 34: bottom side [0080] 35: cable [0081] 36: top surface [0082] 37: top side [0083] 38: top part [0084] AV1: first average wheel signal [0085] AV2: second average wheel signal [0086] DIF: difference signal [0087] d: distance [0088] f: distance [0089] IAV2: intermediate second average wheel signal [0090] m: maximum amplitude [0091] S1-S5: steps [0092] SUB: subset [0093] SW1: first set of wheel signals [0094] SW2: second set of wheel signals [0095] z: vertical direction
